Study of Ni(II), Cu(II), Pb(II), and Zn(II) Removal Using Sludge and Minerals Followed by MF/UF

This work examined the removal of heavy metals in a system consisting of ultrafiltration (UF) or microfiltration (MF) membranes combined with sludge and minerals. The metals under examination were Ni(II), Cu(II), Pb(II), and Zn(II), while the system performance was investigated with respect to several operating parameters. Metal removal was achieved through various processes including chemical precipitation, biosorption, adsorption, ion exchange, and finally retention of the metals by the membranes. The pH had a profound effect on metal removal, as the alkaline environment favored the metal removal process. The use of sludge resulted in increased levels of metal uptake which was further enhanced with the addition of minerals. The metal removal mechanisms depended on the pH, the metal, and mineral type. The combined sludge?Cmineral?CUF system could effectively remove metal ions at an alkaline environment (pH?=?8), meeting the US EPA recommended long-term reuse limits of lead and copper and the short-term reuse limits of nickel and zinc for irrigation purposes, provided that specific mineral dosages were added.     

Use of Power Plant Ash to Remove and Solidify Heavy Metals from a Metal-finishing Wastewater

This laboratory-scale study investigated initially the potential of heavy metal removal from a metal-finishing wastewater using fly and bottom ash from a power plant as coagulants. It was found that the maximum heavy metal content in the ash–sludge mix was obtained at a fly ash-to-bottom ash ratio of 1.5:1 and a stirring time of 3 h, which resulted in heavy metal removal (i.e., Cr, Ni, Cu, Zn, Cd, and Pb) in excess of 99%, with effluent concentrations below the corresponding regulatory standards of Thailand. Furthermore, the feasibility of using fly ash as an admixture to stabilize and solidify the ash–sludge mix generated previously was explored. Results indicated that the stabilization/solidification process can achieve a high level of heavy metal removal efficiency from the ash–sludge mix. The optimum ratio regarding chromium leaching was found to be 1:0.75:0.75 (cement:fly ash:ash–sludge). In addition, the compressive strength and the chromium leaching concentration of the solidified sludge were within acceptable levels for secure landfill disposal and/or use as a construction material.     

Heavy metal and volatile organic chemical removal and treatment in on-site wastewater infiltration systems

Solvents, greases, and rinse waters from routine vehicle maintenance contain heavy metals and volatile organic chemicals (VOCs). In Wisconsin, these fluids enter catch basins along with rinsing waters and are discharged to soil infiltration systems drainfields after mixing with domestic wastewaters in a septic tank. The purpose of this study was to monitor heavy metal and VOC removal and treatment in catch basins and septic tanks at four publicly-owned motor vehicle service stations (MVSS). Cadmium, chromium, and lead were found in catch basin wastewater, septic tank effluent, and septic tank sludge at concentrations ranging from 0.002–7.7 mg L^?1. Lead was found in the highest concentration. The highest concentrations of metals were in septic tank sludge. Of the >50 VOCs scanned for in catch basin wastewater, septic tank effluent, and septic tank sludge samples, 29 were found in concentrations that exceeded analytical detection limits. Concentrations of detected VOCs ranged from 1.0–15,800 µg L^?1 and the highest concentrations of VOCs were found in catch basin wastewater and septic tank sludge. Acetone, ethylbenzene, toluene, and xylenes were the most commonly found VOCs at all sampling locations. Thus, heavy metals and VOCs were not completely removed in catch basins and were discharged to septic tanks where removal occured possibly as these contaminants settled with solids in the sludge. The level of treatment was, however, inadequate and heavy metals and VOCs were discharged to drainfields.     

Operational Optimisation of Pilot Scale Biological Nutrient Removal at the Ciudad Real (Spain) Domestic Wastewater Treatment Plant

The aim of this work is optimising operating conditions for a possibleimplementation of a Biological Nutrient Removal (BNR) process in the Wastewater Treatment Plant (WWTP) of Ciudad Real (Spain). Several factors (hydraulic retention times, anaerobic nitrate concentration, sludge age and wastewater biodegradability) were tested using a pilot scale VIP (Virginia Initiative Plant) activated sludge process and domestic wastewater from the full scale plant. Hydraulic retention times used did not cause changes in N and P removal. P removal was adversely affected by anaerobic NO₃ ^- and improved with higher BOD₅/COD ratios in wastewater. Influence of sludge age was very low in P removal, but N removal was mainly affected by this factor. Final operating conditions were selected taking into account their effects over one of both nutrients. COD and SS removal were always successful. N removal was also easily reached and the main difficulty was P removal. P sludge content was very low (2.5–4%) approximately and was also affected by the same factors tested. The main factor to improve P removal was supposed to be the organic wastewater composition. Wastewater characteristics were modified by using different sources from the WWTP. Volatile fatty acids (VFA) addition to the wastewater by using supernatant of the anaerobic sludge digesters seemed to be the best practical solution for a future BNR implementation in the WWTP.     

Effect of the Heavy Metals Cu,Ni, Cd and Zn on the Growth and Reproduction of Epigeic Earthworms (E. fetida) during the Vermistabilization of Municipal Sewage Sludge

In order to enhance the removal of heavy metals such as Ni, Cu, Zn and Cd from wastewater, different cow dung/sewage sludge ratios were tested to assess the effect of these metals on the adaptability of Eisenia fetida earthworms to the treatment process carried out in a typical plant located in Tamaulipas, Mexico. Two experimental water treatment setups were proposed. The first set of experiments was planned to determine the adequate sewage sludge/cow dung ratio(s), whereas the second arrangement was designed to evaluate the growth performance and fecundity of the earthworms under high heavy metal concentrations. To achieve the objectives, the experiments were conducted for 90 days under controlled environmental conditions. Maximum worm biomass and growth rates were attained in samples containing 25 wt.% of sewage sludge. Weight and mortality of worms were significantly affected by the high levels of heavy metals, making difficult the metal accumulation in the worm tissues.     

Na+和K+共存对A2/O工艺脱氮除磷效果及污泥性质的影响

为了揭示多种金属离子共存的含盐废水生物处理系统污染物的去除机制和污泥特性,考察Na~+、K~+共存对A~2/O工艺污染物去除率、污泥性质和微生物群落的影响,采用高通量测序技术分析了厌氧区、缺氧区和好氧区的微生物群落结构,结合脱氮除磷效果和污泥性质的变化,探讨不同Na~+/K~+摩尔比下A~2/O工艺优势种群的演替规律,以期从微生物角度明确Na~+、K~+共存对含盐废水污染物去除率的影响。结果表明:当进水Na~+/K~+摩尔比分别为2、1和0.5时,A~2/O工艺的COD去除率分别为80%、84%和86%,TN去除率分别为73%、77%和80%,K~+浓度的提高缓解了Na~+对COD和TN去除率的抑制作用;厌氧区释磷率分别为70%、73%和74%,缺氧区吸磷率分别为53%、55%和58%,好氧区吸磷率分别为70%、72%和75%。随着进水Na~+/K~+摩尔比的降低,厌氧区、缺氧区和好氧区微生物群落的丰富度和多样性降低,微生物群落差异显著,变形菌门的相对丰度均升高约30%,拟杆菌门和绿弯菌门相对丰度逐渐降低。陶氏菌属和固氮弧菌属作为优势菌属,其相对丰度逐渐增大,有利于氮磷污染物的去除。通过增加K~+的浓度有利于提高氮、磷去除率,增强污泥的生物絮凝性和反硝化聚磷菌的活性。     

Laboratory Study on the Mobility of Major Species in Fly Ash–Brine Co-disposal Systems: Up-flow Percolation Test

Soil pollution is a universal environmental issue, and the clean-up of contaminated soils can be costly and time consuming. Traditional methods often do not provide an effective solution when it comes to fine-grained and highly impermeable soils and/or immobile contaminants. Electro-remediation, however, is a promising technique. The aim of this study was to relate electrokinetic removal of heavy metals from a contaminated, aged sediment sludge to the metal speciation in the sludge. Metal speciation was determined by a Tessier-based sequential extraction method. Two electro-remediation experiments were conducted in the laboratory in order to investigate removal of metals. The studies were done in a cell designed for a predictive laboratory test of feasibility of electro-remediation of soil. Maximum removal percentages during the experiment using a constant current of 1 mA/cm² over ～180 h with a corresponding potential gradient of 0.5 V/cm were larger than 15 % for Cd (21 %), Cu (15 %), and Zn (23 %); Ni and Pb showed removal less than 10 %; Cr demonstrated no removal. Removal of non-contaminant metals Mn and Ca exceeded that of heavy metals. The removal rates were compared to metal speciation in the non-treated sludge, measured by the sequential extraction. It was observed that the electrokinetic removal did not directly relate to the metal distribution over the fractions within the sludge. The aging of metals and other geochemical characteristics of the contaminated sludge affected the removal of heavy metals. Therefore, sequential extraction alone does not provide a predictive tool for the effectiveness of electro-remediation. Additional geochemical information is needed.     

Evaluation of Ultrafiltration Process Performance for Treatment of Petroleum Contaminated Waters

A series of 2⁴ factorial design experiments were performed to study the effects of source water type, contaminant concentration, prefiltration and use of a coagulant on the performance of ultrafiltration process (UF) for treatment of waters contaminated with petroleumhydrocarbons (PHCs). The process performance was evaluated in terms of initial flux through the membrane, fouling time and PHC removal efficiency. The higher levels of PHC contamination significantly decreased the initial flux, membrane life and PHC removal efficiency. Coagulation pretreatment significantly improved the membrane life and PHC removal efficiency with no significant effect on theinitial flux. Prefiltration to remove the flocs from the coagulated water samples did not improve the fouling time but improved the PHC removal efficiency.     

Removal of Pb(II), Cr(III) and Cr(VI) from Aqueous Solutions Using Alum-Derived Water Treatment Sludge

The sorption of Pb(II), Cr(III) and Cr(VI) from aqueous solution using alum-derived water treatment sludge was investigated using the batch adsorption technique. Samples of sludge from two separate water treatment plants were used (one where alum was used alone and one where it was used in combination with activated C). The sorption characteristics of the two samples were generally very similar. Sorption isotherm data for all three ions fitted equally well to both Freundlich and Langmuir equations. Maximum sorption capacity and indices of sorption intensity both followed the order: Cr(III)?>?Pb(II)?>?Cr(VI). Kinetic data correlated well with a pseudo-second-order kinetic model suggesting the process involved was chemisorption. Sorption was pH-dependant with percentage sorption of Cr(III) and Pb(II) increasing from <30% to 100% between pH?3 and 6 whilst that of Cr(VI) declined greatly between pH?5 and 8. HNO₃ at a concentration of 0.1?M was effective at removing sorbed Cr(III) and Pb(II) from the sludge surfaces and regeneration was successful for eight sorption/removal cycles. It was concluded that water treatment sludge is a suitable material from which to develop a low-cost adsorbent for removal of Cr and Pb from wastewater streams.     

Biokinetic behavior and settling characteristics in an activated sludge under the effect of toxic Ni(II) influentes

The inhibitory effect of Ni upon a biological system of activated sludge has been analyzed in two semicontinuous sequential reactors feeding synthetic wastewater. One of the reactors was used as control while in the other given amounts of NiSO₄ were added to the influent to achieve a concentration of 30 ppm Ni(II). An analysis of the characteristic biokinetic parameters has been made and the correspondence with the operating conditions stated. A series of O₂ uptake tests were proposed and the results analyzed together with the specific rate of substrate removal (U) in order to explain the toxic influence of Ni(II). An accumulation of undigested substrate on the floes seems to explain certain aspects derived of the presence of Ni. The sludge residence time (SRT), within a certain range, can be used as a control operating variable to mitigate the inhibitory effect of Ni, since a somewhat contrary effect upon the settling characteristics of the sludge must be also considered.     

The influence of process parameters on the removal of heavy metals in activated sludge

The behavior of six heavy metals in an activated sludge pilot plant under conditions of normal and elevated influent metal concentrations has been studied. Percentage heavy metal removals at sludge ages of 4, 9, and 12 d were more consistent when metals were added to the system, possibly as a result of lesser variations in heavy metal speciation in the settled sewage, and the greatest degree of accumulation of heavy metals by the biomass occurred at the 12 d sludge age. When shock loads of heavy metals were introduced into the system, their concentrations in the effluent did not immediately rise in proportion; however, heavy metal removal efficiencies were similar under steady state conditions of normal and elevated influent metal concentrations. Cadmium, Cu, and Ni were largely soluble in the effluent samples, but Cr, Pb, and Zn were predominantly insoluble, indicating that particulate forms of these metals may escape removal in secondary sedimentation. The high degree of Ni solubility in the settled sewage and final effluent reflected its consistently poor removal in the process. The two most soluble metals, Cu and Ni, appeared to be associated to a large degree with high molecular weight substances in the settled sewage and final effluent, possibly influencing their availability for uptake by the biomass.     

絮凝预处理对奶牛场膜生物反应器膜污染影响的中试试验

为探讨经济实用的高浓度奶牛场污水预处理方法,该研究开展了絮凝预处理对膜生物反应器（Membrane Bioreactor,MBR）膜污染的影响试验,试验采用高浓度奶牛场污水原水和絮凝出水作为MBR进水依次运行,对比分析了不同进水的膜污染规律及其原因。结果表明,絮凝出水作为MBR进水时膜污染速率较污水原水降低47%且膜组件的维护性清洗时间间隔由10 d延长至16 d;MBR处理污水原水的膜池混合液中胞外聚合物（Extracellular Polymeric Substances,EPS）和溶解性微生物产物（Soluble Microbial Products,SMP）浓度分别为4.76和3.94 g/L,而处理絮凝出水时的EPS和SMP浓度值分别为3.97和2.23 g/L。两阶段MBR膜池混合液各粒径值总体上均呈现先增大后减小的趋势,第1和第2阶段的最大粒径体积百分比分别出现在第16天和第23天,第1阶段EPS浓度和SMP浓度均随着颗粒粒径的增大而减小,第2阶段EPS浓度随着颗粒粒径的增大而增大但SMP浓度与颗粒物粒径之间无变化规律;MBR处理污水原水的膜池混合液颗粒粒径的峰值较分散,且16 d后峰值向小粒径方向移动,而处理絮凝出水的峰值粒径相对稳定,且峰值粒径对应的最大体积百分比从3.57%增加至5.95%。MBR对2种进水的化学需氧量（Chemical Oxygen Demand,COD）去除率均可达90%以上,氨氮（Ammonia Nitrogen,NH3-N）去除率均接近90%,对絮凝出水的总磷（Total Phosphorus,TP）处理效果高于污水原水。絮凝预处理使膜池混合液的EPS和SMP浓度降低且SMP蛋白质浓度显著降低（P<0.05）、膜池混合液颗粒粒径显著增加（P<0.05）,有效减缓了MBR的膜污染,絮凝预处理与MBR组合可望为高浓度奶牛场污水处理提供可靠的技术途径。     

污水处理反硝化除磷-诱导结晶磷回收工艺中除磷微生物特性

为探究反硝化除磷-诱导结晶磷回收工艺中缺氧池污泥释磷、吸磷以及微生物特征,利用荧光原位杂交(fluorescence in situ hybridization,FISH)技术、电子扫描显微镜(scanning electron microscope,SEM)观察了微生物的数量、分布和形态;通过批次试验考察了污泥在厌氧/好氧和厌氧/缺氧2种模式下的释磷和吸磷特征。结果表明:该双污泥系统缺氧池中聚磷菌占总细菌比例的69.7%,明显高于单污泥系统中富集的聚磷菌比例,污泥中的微生物多呈杆状;厌氧/好氧、厌氧/缺氧模式下单位污泥浓度(mixed liquor suspended solids,MLSS)总吸磷量(以PO43--P计)分别为22.84、18.60 mg/g,反硝化聚磷菌(denitrifying polyphosphate-accumulating organisms,DPAO)占聚磷菌(polyphosphate-accumulating organisms,PAO)的比例为81.44%,表明在长期的厌氧/缺氧运行条件下可以富集到以硝酸盐为电子受体的反硝化聚磷菌,同时还存在着仅以氧气为电子受体的聚磷菌;通过pH值和氧化还原电位(oxidation reduction potential,ORP)的实时监测可以快速地了解污水生物处理系统中各类反应的进程,对调控工艺参数有着重要的意义。综上所述,为保证污水生物处理工艺的正常稳定运行,将微生物分析与常规的化学参数分析结合起来考察将是未来发展的必然趋势。     

Distribution of Metal Extractable Fractions during Anaerobic Sludge Treatment in Southern Spain WWTPs

A new European Union legislation on sludge treatment isbeing introduced that will replace the one currently in force.The control of heavy metals is an important aspect of this newlegislation. The most common methodology to examine the metalcontent of sludges is determination of total metal contentafter total or pseudo total digestion of the sludge samples.Nevertheless, this kind of analysis is not informative on theavailability or mobility of the metals; a metal speciationanalysis is therefore required. In this study, sludge samplesfrom conventional activated sludge wastewater treatment plants(WWTP) were collected at different stages of an anaerobicsludge treatment process. In these samples, the total metalcontent and the distribution of metal species were determined(Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti, Zn) followinga protocol of sequential extraction. Only 14% of the metalwas present in readily available forms in the treated sludges.In composted sludges, this value dropped to 6%.     

Can Vegetal Biopolymers Work as Coagulant–Flocculant Aids in the Treatment of High-Load Cosmetic Industrial Wastewaters?

The aim of this work was to evaluate the role of three biopolymers used as coagulant?Cflocculant aids in the treatment of a high-load cosmetic industry wastewater (WW) located in Mexico. Discussion is based on a surface response methodology. When using guar, locust bean gum, and Opuntia mucilage, conductivity and turbidity removals as high as 20.1 and 67.8?% were found, respectively. Chemical oxygen demand (COD) removals as high as 38.6?% were observed. The maximum removal efficiency was found for mucilage, with 21.1?mg?COD/mg polymer. At the end of the process, pH was in the range of 5.8?C7.3 for an initial wastewater pH value of 5.6. The production of sludge was very dependent on the WW organic load. An analysis of some metal content in the sludges is presented. From the response surface analysis, it was observed that the parameter which strongly affected the removal of COD, turbidity, oil and greases (O&G), and the amount of sludge including their metal contents was the polymer dose. Only in the case of O&G removal was a combination of dose?Cwastewater organic load responsible for the removals. The values of R ² for the correlation process were between 0.5451 (O&G) and 0.7989 (COD). The p values for the different expressions were between 0.1985 (COD) and 0.7195 (O&G). The values of adequate precisior (AP) indicate how feasible it is to use the surface response analysis (AP?>?4). Most of the analysis indicated that AP?>?4, except in the case of the O&G removal analysis where AP?=?2.9.     

Mercury pathways in municipal wastewater treatment plants

A nine-week sampling and analysis program was completed at a large municipal wastewater treatment plant to characterize the fate of Hg entering the plant. Mercury removal in primary treatment averaged 79%, and the average Hg removal across the entire plant was approximately 96%. Mercury loadings on the secondary (activated sludge) treatment process were elevated to near plant influent levels due to the recycle of spent scrubber water from sewage sludge incinerator emissions control equipment. This internal recycle of spent incinerator scrubber water resulted in elevated Hg loadings to the incinerators, and effectively reduced the Hg control efficiency of the emissions control equipment to near zero. Measurements indicate that approximately 95% of the Hg mass entering the plant is discharged to the atmosphere via sludge incinerator emissions. These results indicate that municipal wastewater treatment facilities can remove Hg from wastewater quite effectively; however, where wastewater sludge is incinerated, almost the entire mass of Hg removed from the wastewater can be discharged to the atmosphere.     

Heavy Metal Release from Some Industrial Wastes: Influence of Organic and Inorganic Acids, Clay Minerals, and Nanoparticles

Knowledge about heavy metal release from industrial solid wastes(ISWs) is crucial for better management of their environmental risks. This study was conducted to investigate the effect of organic and inorganic acids, clay minerals, and nanoparticles(NPs) on the release of heavy metals from sugar factory waste, ceramic factory waste, leather factory waste, and stone cutting waste. The influence of the extractants on heavy metal release from these ISWs was in the following descending order: citric acid oxalic acid nitric acid≥ sulfuric acid Ca Cl2. Addition of clay minerals and NPs as adsorbents decreased heavy metal release, which was significantly lower in NP-treated wastes than in the clay mineral-treated wastes. On the other hand, the presence of organic and inorganic acids increased heavy metal adsorption by NPs and clay minerals. These results suggest that NPs can be applied successfully in waste remediation,and organic and inorganic acids play an important role in the removal of heavy metals from the studied adsorbents.     

Dewatered anaerobically‐stabilized primary sewage sludge composting: Metal leachability and uptake by natural Clinoptilolite

Abstract

Environmental problems associated with sewage sludge disposal have prompted strict legislative actions over the past years. At the same time, the upgrading and expansion of wastewater treatment plants have greatly increased the volume of sludge generated. The major limitation of land application of sewage sludge compost is the potential high heavy metal content in relation to the metal content of the original sludge. Composting of sewage sludge with natural zeolite (Clinoptilolite) can enhance its quality and suitability for agricultural use. Clinoptilolite has the ability to uptake heavy metals in satisfactory levels. Finally, in order to estimate the metal leach ability of the final product of compost, the Generalized Acid Neutralization Capacity (GANC) procedure was used and was found that by increasing the leachate pH, the heavy metal concentration decreases.     

城市污水污泥处置利用及其影响因素分析

重金属对污泥最终处置利用具有很大影响,有时甚至决定了技术路线的选择.论文从分析西安市3个污水处理厂污泥重金属含量和浸出量的检测结果出发,对我国污水污泥处置利用相关标准与危险废物鉴定标准进行研究.结果表明:我国污泥处置现行标准对重金属的迁移特性不够重视,应当建立重金属总量指标与形态指标(浸出毒性)相结合的污泥处置控制标准体系;在进行污水处理厂泥质分析的基础上,探索西安市较为可行的污泥处置利用方式,提出西安市污水污泥处置利用的2条途径:填埋和能源利用.     

Hydraulic Retention Time Influence on Improving Flocculation in the Activated Sludge Processes Through Polyelectrolytes

Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L^?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times.